Method of operating an internal combustion engine

Abstract

An internal combustion engine, in particular for a motor vehicle, in which fuel may be injected into a combustion chamber during an intake phase in a first mode of operation or during a compression phase in a second mode of operation, and in which exhaust gases may be sent to a catalytic converter. A control unit determines a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature. In addition, at least one additional injection after combustion is implemented by the control unit as a function of the temperature difference.

What is claimed is:  
     
       1. A method of operating an internal combustion engine which includes a combustion chamber and a catalytic converter for receiving exhaust gases, the method comprising: 
       injecting fuel into the combustion chamber during one of:  
       (a) an intake phase in a first mode of operation, and  
       (b) a compression phase in a second mode of operation;  
       determining a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point of the engine having a low exhaust gas temperature;  
       inducing at least one additional injection after combustion as a function of the temperature difference;  
       specifying a minimum lambda value of the exhaust gas; and  
       limiting an amount of the at least one additional injection after combustion as a function of the minimum lambda value.  
     
     
       2. The method of  claim 1 , wherein the internal combustion engine is incorporated in a motor vehicle. 
     
     
       3. A method of operating an internal combustion engine which includes a combustion chamber and a catalytic converter for receiving exhaust gases, the method comprising: 
       injecting fuel into the combustion chamber during one of:  
       (a) an intake phase in a first mode of operation, and  
       (b) a compression phase in a second mode of operation;  
       determining a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature;  
       inducing at least one additional injection after combustion as a function of the temperature difference;  
       specifying a fixed lambda value of the exhaust gas;  
       setting an amount of the at least one additional injection after combustion as a function of the fixed lambda value; and  
       modifying a start of injection of the at least one additional injection.  
     
     
       4. The method of  claim 3  wherein the internal combustion engine is incorporated in a motor vehicle. 
     
     
       5. The method of  claim 3 , further comprising: 
       modifying a start of injection as a function of the actual exhaust gas temperature.  
     
     
       6. The method of  claim 1 , further comprising: 
       selecting at least one of: i) a number of the at least one additional injection, and ii) times of the at least one additional injection, so that at least one of the following:  
       the catalytic converter does not drop below an operating temperature, and  
       the catalytic converter does not overheat.  
     
     
       7. The method of  claim 1 , wherein the method is implemented during an idling of the internal combustion engine. 
     
     
       8. The method of  claim 1 , further comprising: 
       injecting fuel into the combustion chamber of the engine during the second mode of operation of the internal combustion engine.  
     
     
       9. A control element for a control unit of an internal combustion engine, the internal combustion engine including a combustion chamber and a catalytic converter for receiving exhaust gases, the control element comprising: 
       a storage element adapted to store a program having instructions for directing the control unit to control and execute:  
       injection of fuel into the combustion chamber during one of:  
       (a) an intake phase in a first mode of operation of the engine, and  
       (b) a compression phase in a second mode of operation of the engine,  
       determination of a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point of the engine having a low exhaust gas temperature,  
       provision of at least one additional injection after combustion as a function of the temperature difference,  
       specification of a minimum lambda value of the exhaust gas, and  
       limitation of an amount of the at least one additional injection after combustion as a function of the minimum lambda value.  
     
     
       10. The control element of  claim 9 , wherein the control element includes flash memory, the program stored on the control element is executable using a microprocessor and the internal combustion engine is incorporated in a motor vehicle. 
     
     
       11. A control unit for an internal combustion engine, the internal combustion engine including a combustion chamber and a catalytic converter for receiving exhaust gases, the control unit comprising: 
       a processor configured to control:  
       injection of fuel into the combustion chamber during one of:  
       (a) an intake phase in a first mode of operation of the engine, and  
       (b) a compression phase in a second mode of operation of the engine,  
       determination of a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature,  
       implementation of at least one additional injection after combustion as a function of the temperature difference,  
       specification of a minimum lambda value of the exhaust gas,  
       limitation of an amount of the at least one additional injection after combustion as a function of the minimum lambda value.  
     
     
       12. The control unit of  claim 11 , wherein the internal combustion engine is incorporated in a motor vehicle. 
     
     
       13. An internal combustion engine, comprising: 
       a combustion chamber in which fuel may be injected during one of:  
       an intake phase in a first mode of operation, and  
       a compression phase in a second mode of operation;  
       a catalytic converter for receiving exhaust gases; and  
       a control unit, the control unit configured to determine a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature, and to induce at least one additional injection after combustion as a function of the temperature difference;  
       wherein a minimum lambda value of the exhaust gas is specified and the control unit limits an amount of the at least one additional injection after combustion as a function of the minimum lambda value.  
     
     
       14. The internal combustion engine of  claim 13 , wherein the internal combustion engine is incorporated in a motor vehicle. 
     
     
       15. A control unit for an internal combustion engine, the internal combustion engine including a combustion chamber and a catalytic converter for processing exhaust gases, the control unit comprising: 
       a processor configured to control:  
       injection of fuel into the combustion chamber during one of:  
       a) an intake phase in a first mode of operation of the engine, and  
       b) a compression phase in a second mode of operation of the engine,  
       determination of a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature,  
       a setting of an amount of at least one additional injection after combustion as a function of the temperature difference,  
       specification of a fixed lambda value,  
       implementation of the at least one additional injection after a combustion as a function of the fixed lambda value, and  
       modification of a start of injection of the at least one additional injection.  
     
     
       16. The control unit of  claim 15 , wherein the internal combustion engine is incorporated in a motor vehicle. 
     
     
       17. An internal combustion engine for a motor vehicle comprising: 
       a combustion chamber in which fuel may be injected during one of an intake phase in a first mode of operation and a compression phase in a second mode of operation;  
       a catalytic converter configured to receive exhaust gases;  
       a control unit configured to determine a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature, and implementing at least one additional injection after combustion as a function of the temperature difference;  
       wherein a fixed lambda value of the exhaust gas is specified, the control unit sets an amount of the at least one additional injection after combustion as a function of the fixed lambda value, and modifies the start of injection of the at least one additional injection.  
     
     
       18. A control unit for an internal combustion engine, the internal combustion engine including a combustion chamber and a catalytic converter for receiving exhaust gases, the control unit comprising: 
       a processor configured to control:  
       injection of fuel into the combustion chamber during one of:  
       (a) an intake phase in a first mode of operation, and  
       (b) a compression phase in a second mode of operation;  
       determination of a temperature difference between an actual exhaust gas temperature and a setpoint exhaust gas temperature at an operating point having a low exhaust gas temperature;  
       an inducing of at least one additional injection after combustion as a function of the temperature difference;  
       a specifying of a fixed lambda value of the exhaust gas;  
       a setting an amount of the at least one additional injection after combustion as a function of the fixed lambda value; and  
       a modification of a start of injection of the at least one additional injection.